Baroreflex unimpaired by operant avoidance or classical aversive conditioning in dogs

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Regulation
• Behavioral Neuroscience

Background:

• Previous research indicated baroreflex heart rate control is impaired during aversive conditioning.
• The impact of emotionally stressful paradigms on baroreflex arterial pressure control remained unexamined.

Purpose of the Study:

• To investigate the effects of operant shock avoidance and classical aversive conditioning on baroreflex control of arterial pressure.
• To determine if baroreceptor function or the baroreflex operating range is altered during these conditioning paradigms.

Main Methods:

• Utilized dogs with surgically prepared carotid sinus regions for reversible isolation.
• Derived complete stimulus-response curves for carotid sinus pressure effects on heart rate and arterial pressure under neutral and conditioning conditions.

Main Results:

• Arterial pressure and heart rate were elevated during conditioning, indicating baroreflex resetting, but baroreceptor thresholds and saturation points were unchanged.
• The range of baroreflex control for arterial pressure and heart rate increased significantly during both conditioning types.
• Baroreflex gain remained unchanged during operant conditioning but increased during classical conditioning.

Conclusions:

• The baroreflex is not impaired during operant shock avoidance or classical aversive conditioning in dogs.
• The baroreflex undergoes resetting during these stressful conditions, regulating blood pressure at a higher level.
• These findings highlight the dynamic adaptability of the baroreflex under emotional stress.